1. Filed of the Invention
The present invention relates to a lens molding apparatus used for forming a molded lens by preparing an annular forming frame having on its inner peripheral surface an annular stepped portion, oppositely abutting, on the annular stepped portion, a pair of lens forming molds for forming outer shapes of both surfaces of a molded lens to be manufactured, injecting a molding resin in a space between the opposed lens forming molds, and irradiating the molding resin with ultraviolet rays to harden the molding resin; and to a lens molding tool used for the lens molding apparatus.
2. Description of the Related Art
Conventionally, a lens molding tool 1 shown in FIG. 1 has been known. The lens molding tool 1 has a silicon made annular forming frame 2 having on its inner peripheral side an annular stepped portion 3 for specifying the thickness of a molded lens. Glass made lens forming molds 5 and 6 for forming outer shapes of both surfaces of a molded lens are abutted, oppositely in the thickness direction, on the annular stepped portion 3, to form a target space 7. The forming frame 2, which is slightly deformable, is partly turned over to form a clearance between the lens forming mold 5 and the forming frame 2, and a molding resin 8 is injected in the target space 7 through the clearance between the lens forming mold 5 and the forming frame 2.
The lens molding tool 1 into which the molding resin 8 has been injected is set on a lens molding apparatus, and the molding resin 8 is hardened by irradiating the molding resin 8 with ultraviolet rays, to form a hardened molded lens.
The related art lens molding tool 1, however, has a problem. If the lens forming molds 5 and 6 are tilted to the forming frame 2, there may be produced a prism component in the molded lens hardened by irradiating the molding resin 8 with ultraviolet rays.
Another problem of the related art lens molding tool 1 lies in variations in thickness of molded lenses as finished products. As described above, the related art lens molding tool 1 has a structure in which part of the forming frame 2 is turned over to form a clearance; the molding resin 8 is injected in the target space 7 through the clearance; and the clearance is blocked by pressing the lens forming mold 5 to the annular stepped portion 3 before irradiation of the molding resin 8 with ultraviolet rays. Accordingly, in the structure of the related art lens molding tool 1, a clearance is liable to be formed between the lens forming mold 5 and the annular stepped portion 3. The related art structure is also inconvenient in that the lens forming molds 5 and 6 tend to be tilted to the forming frame 2 because the lens forming molds 5 and 6 are set on the forming frame 2 only by abutting the lens forming molds 5 and 6 on the annular stepped portion 3, and that although the lens forming molds 5 and 6 are pressed on the annular stepped portion 3 after injection of the molding resin 8 in the target space 7, there is such a possibility, on the basis of any reason, that a clearance is formed between the lens forming mold 5 and the annular stepped portion 3 or the annular stepped portion 3 is distorted when being pressed by the lens forming mold 5. In each case, a gap between the lens forming molds 5 and 6 may largely offset from a reference gap specified based on the thickness of the annular stepped portion 3, resulting in variations in thickness of molded lenses as finished products.
It is undesirable that a prism component be carelessly contained in a molded lens used for a spectacle lens, and that a thickness of the molded lens be largely varied over a tolerance. For these reasons, there have been strong demands to develop a lens molding apparatus capable of simply manufacturing molded lenses while preventing a prism component from being carelessly contained in the molded lens and suppressing variations in thickness of the molded lenses as much as possible, and a lens molding tool used for the lens molding apparatus.
An object of the present invention is to provide a lens molding apparatus capable of measuring optical characteristics of a molded lens in a state being before irradiation of a molding resin of the molded lens with ultraviolet rays, that is, in a state in which the molded lens is unhardened.
Another object of the present invention is to provide a lens molding apparatus capable of suppressing variations in thickness of molded lenses as much as possible and a lens molding tool used for the lens molding apparatus.
To achieve the above object, according to a first aspect of the present invention, there is provided a lens molding apparatus basically including a lens molding tool in which a molding resin is injected in a space formed by opposed lens forming molds to form an unhardened molded lens, wherein the unhardened molded lens is hardened by irradiating the unhardened molded lens with ultraviolet rays. The above lens molding apparatus is characterized by including a measuring system for measuring optical characteristics of the hardened molded lens.
In the lens molding apparatus according to the first aspect of the present invention, since optical characteristics of a molded lens are estimated using the measuring system directly after hardening the molded lens, it is possible to check, before the subsequent lens coating step, an inconvenience of the hardened molded lens due to erroneous selection of the forming frame.
According to a second aspect of the present invention, there is provided a lens molding apparatus basically including a lens molding tool in which a molding resin is injected in a space formed by opposed lens forming molds to form an unhardened molded lens, wherein the unhardened molded lens is hardened by irradiating the unhardened molded lens with ultraviolet rays. The above lens molding apparatus is characterized by including a measuring system for measuring optical characteristics of the unhardened molded lens.
In the lens molding apparatus according to the second aspect of the present invention, optical characteristics such as refractivity, cylindricity, axial angle, and prism component, of a molded lens as a finished product can be estimated before hardening of the molding resin.
According to a third aspect of the present invention, there is provided a lens molding tool including: an annular forming frame; a pair of lens forming molds for forming outer shapes of both surfaces of a molded lens, the forming molds being oppositely arranged on both sides of the forming frame in the thickness direction to form a target space into which a molding resin is to be injected; and a pressing jig for pressing the pair of lens forming molds.
In the lens molding tool according to the third aspect of the present invention, since the molding resin can be hardened by irradiating the molding resin with ultraviolet rays in a state in which the pair of lens forming molds are pressed by the pressing jig, it is possible to reduce variations in thickness of molded lenses as finished products.